A5018769135- Spectroscopy and Quantum Chemical Studies
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Advanced Chemical Physics Studies
- Quantum chaos and dynamical systems
- Quantum Mechanics and Applications
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Luminescence and Fluorescent Materials
- Metal-Organic Frameworks: Synthesis and Applications
- Molecular spectroscopy and chirality
- Quantum Information and Cryptography
- Covalent Organic Framework Applications
- Fuel Cells and Related Materials
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Laser Applications
- Molecular Junctions and Nanostructures
- Electrocatalysts for Energy Conversion
- Photochromic and Fluorescence Chemistry
- Machine Learning in Materials Science
- Laser-Matter Interactions and Applications
- Perovskite Materials and Applications
- Graphene research and applications
- Nanoplatforms for cancer theranostics
- Metal-Catalyzed Oxygenation Mechanisms
University of South Carolina Sumter
2003-2025
University of South Carolina
2015-2024
Northwestern University
2005-2006
University of Chicago
2000-2001
University of Notre Dame
1996-1999
Electronic structure modulation of metal-organic frameworks (MOFs) through the connection linker "wires" as a function an external stimulus is reported for first time. The established correlation between MOF electronic properties and photoisomerization kinetics well changes in absorption profile unprecedented extended well-defined structures containing coordinatively integrated photoresponsive linkers. presented studies were carried out on both single crystal bulk powder with preservation...
Cooperative behavior and orthogonal responses of two classes coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example a photo-thermo-responsive hierarchical platform. Synergetic to temperature excitation wavelength are achieved by confining stimuli-responsive moieties within metal-organic framework (MOF), leading preparation novel spiropyran-diarylethene based material. Synergistic photoswitches enables study resonance energy...
Herein, we examine pathway complexity in the supramolecular polymerization of a novel m-terphenyl bis-urea macrocycle. Designed to induce kinetically metastable states, macrocycle's concentration-dependent aggregation was studied via ¹H NMR and IR spectroscopy THF CHCl₃. Temperature-dependent UV-Vis water/THF revealed cooperative nucleation-growth mechanism, indicated by shift λmax longer wavelengths upon cooling. Morphological studies using DLS, AFM, SEM demonstrated fibrous aggregate...
Calculation of chemical reaction dynamics is central to theoretical chemistry. The majority calculations use either classical mechanics, which computationally inexpensive but misses quantum effects, such as tunneling and interference, or expensive often conceptually opaque. An appealing middle ground the semiclassical mechanics. Indeed, since early 1970s there has been great interest in using methods calculate probabilities. However, despite elegance S-matrix theory, numerical results on...
Solution of the Schrodinger equation within de Broglie-Bohm formulation is based on propagation trajectories in presence a nonlocal quantum potential. We present new strategy for defining approximate potentials restricted trial function by performing optimal fit to log-derivatives wave density. This procedure results energy-conserving dynamics closed system. For one particular form leading linear force, optimization problem solved analytically terms first and second moments weighted...
We report the first examples of purely organic donor-acceptor materials with integrated π-bowls (πBs) that combine not only crystallinity and high surface areas but also exhibit tunable electronic properties, resulting in a four-orders-of-magnitude conductivity enhancement comparison parent framework. In addition to alkyne-azide cycloaddition utilized for corannulene immobilization solid state, we probed charge transfer rate within Marcus theory as function mutual πB orientation time, well...
Confinement-imposed photophysics was probed for novel stimuli-responsive hydrazone-based compounds demonstrating a conceptual difference in their behavior within 2D versus 3D porous matrices the first time. The challenges associated with photoswitch isomerization arising from host interactions photochromic scaffolds could be overcome materials. Solution-like photoisomerization rate constants were realized sterically demanding hydrazone derivatives solid state through coordinative...
We introduce and investigate a chemical model based on perturbative corrections to the product of singlet-type strongly orthogonal geminals wave function. Two specific points are addressed (i) Overall accuracy such with at leading order; (ii) Quality strong orthogonality approximation in diverse systems. use Epstein-Nesbet form perturbation theory show that its known shortcomings disappear when it is used reference Hamiltonian geminals. Application this various systems reveals well suited...
Development of a general approach to construction efficient high-dimensional bases is an outstanding challenge in quantum dynamics describing large amplitude motion molecules and fragments. A number approaches, proposed over the years, utilize Gaussian whose parameters are somehow—usually by propagating classical trajectories or solving coupled variational equations—tailored shape wave function evolving time. In this paper we define time-dependent through ensemble Bohmian trajectories, known...
Photophysics tunability through alteration of framework aperture (metal–organic (MOF) = variable; guest constant) was probed for the first time in comparison with previously explored concepts (MOF constant; variable). In particular, analysis confinement effect on a photophysical response integrated 5-(3-chlorobenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one (Cl-BI) chromophore allowed us to establish photophysics–aperture relationship. To shed light observed correlation, confined...
We introduce quasirandom distributed Gaussian bases (QDGB) that are well suited for bound problems. The positions of the basis functions chosen quasirandomly while their widths and density potential. function overlap kinetic energy matrix elements analytical. potential accurately evaluated using few-point quadratures, since localized. resulting QDGB can be easily constructed is shown to accurate efficient eigenvalue calculation several multidimensional model vibrational As more demanding...
Similarity of equations motion for the classical and quantum trajectories is used to introduce a friction term dependent on wavefunction phase into time-dependent Schrödinger equation. The describes irreversible energy loss by system. force proportional velocity trajectory. resulting equation nonlinear, conserves normalization, evolves an arbitrary ground state system (of appropriate symmetry if applicable). Decrease in average kinetic trajectory ensemble. Dynamics high regime suitable...
Abstract The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for first time using novel purely organic porous crystalline with covalently bound two‐ and three‐dimensional acceptors. studies towards estimation charge transfer rates as a function acceptor stacking are in line experimentally observed drastic, eight‐fold conductivity enhancement. evaluation redox behavior buckyball‐ or tetracyanoquinodimethane‐integrated conducted. In parallel...
S. Garashchuk, F. Grossmann and D. Tannor, J. Chem. Soc., Faraday Trans., 1997, 93, 781 DOI: 10.1039/A607595I
We present a time-dependent semiclassical method based on quantum trajectories. Quantum-mechanical effects are described via the potential computed from wave function density approximated as linear combination of Gaussian fitting functions. The number functions determines accuracy approximate (AQP). One fit reproduces time-evolution packet in parabolic potential. limit large Gaussians and trajectories gives full quantum-mechanical result. is systematically improvable classical to fully...
In the de Broglie-Bohm formulation of quantum mechanics time-dependent Schrodinger equation is solved in terms trajectories evolving under influence and classical potentials. For a practical implementation that scales favorably with system size accurate for semiclassical systems, we use approximate Recently, have shown optimization nonclassical component momentum operator fitting functions leads to energy-conserving potential. particular, linear give exact time evolution Gaussian wave packet...
Dynamics based on quantum trajectories with approximate potential is generalized to nonadiabatic systems and its semiclassical properties are discussed. The formulation uses the mixed polar-coordinate space representation of a wave function. polar part describes overall time evolution wave-function components semiclassically using single-surface potential. coordinate represents complex``population'' amplitude, which in case localized coupling can be solved for mechanically an efficient...
A massively parallel, direct quantum molecular dynamics method is described. The combines a trajectory (QT) representation of the nuclear wave function discretized into an ensemble trajectories with electronic structure (ES) description electrons, namely using density functional tight binding (DFTB) theory. Quantum effects are included nuclei via corrections to classical forces. To reduce computational cost and increase numerical accuracy, resulting from localization computed approximately...
According to recent experiments, atomically thin hexagonal boron nitride and graphene are permeable protons deuterons (and not other atomic species), the experimental estimates of activation energy lower than theoretical values by about 0.5 eV for isolated proton–membrane transfer model. Our analysis electronic potential surfaces along normal transmission direction, obtained using correlated structure methods, suggests that aqueous environment is essential stabilize proton transmission, as...
The efficient delivery of reactive and toxic gaseous reagents to organic reactions was studied using metal-organic frameworks (MOFs). simultaneous cargo vehicle catalytic capabilities several MOFs were probed for the first time examples aromatization, aminocarbonylation, carbonylative Suzuki-Miyaura coupling reactions. These highlight that can serve a dual role as gas catalyst, leading product formation with yields similar employing pure gases. Furthermore, be recycled without sacrificing...
Cationic metallopolymers represent a new class of ionomers as anion-exchange membranes (AEMs) for transporting hydroxide ions in alkaline fuel cells. In this work, main-chain cobaltocenium-containing polymers with complete hydrocarbon framework were synthesized by ring-opening metathesis polymerization (ROMP) cobaltocenium-fused cycloalkenes and cis-cyclooctene followed backbone hydrogenation. These copolymers varied fractions cobaltocenium exhibit high chemical thermal stability, low...